In recent years, global environmental issues such as measures against global warming have become focused. Carbon dioxide emission caused by the use of fossil fuel such as petroleum has come to an issue. In particular, emissions from gasoline-fueled automobiles and the like have been brought into question.
To address these issues, various electric automobiles have been developed to reduce emissions: for example, solar cars using solar cells as their power source, fuel-cell cars using fuel cells as their power source, hybrid cars using both gasoline and electricity (electric motor) have been developed.
The electric automobiles mentioned above are driven by a gasoline-fueled engine for running on the one hand, and recharge a battery that stores electric energy by driving the engine on the other. Recently, electric cars such as plug-in hybrid cars which can be recharged by plugging into a household wall socket without using an engine have been developed. However, emissions of these automobiles still cause serious problems. Hence, various technologies to help drivers of automobiles to reduce emission have been disclosed.
For example, a technology for calculating and displaying the driving efficiency of a hybrid car to its driver has been disclosed. This technology uses accelerations and instant fuel consumptions of the hybrid car calculated based on the driving distance and the fuel consumption thereof to calculate the driving efficiency (see, for example, Patent Document 1).
Patent Documents
Patent Document 1: Japanese Patent Application Laid-open No. 2007-253727